Control of vascular tone in notothenioid fishes is determined by phylogeny, not environmental temperature

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Colleges, School and Institutes


We examined potential vasomotor control mechanisms in an Antarctic fish (Trematomus bernacchii; usual core temperature approximately -1 degreesC), comparing sensitivity to agonists by means of the cumulative dose response and potency with reference to depolarization by 50 mM KCl. In efferent branchial arteries, norepinephrine (NE) produced similar to 20% of the maximal KCl tension and similar to 40% in the presence of 10(-3) M sotalol, suggesting a modest contribution of alpha- and beta -adrenergic tonus [half-maximal response (pEC(50)) = 6.29 +/- 0.37 M]. Carbachol (CBC) and serotonin (5-HT) had different sensitivities (pEC(50) = 4.50 +/- 0.40 and 6.82 +/- 0.08 M, respectively) but similar potencies (21.6 +/- 11.1 and 31.1 +/- 5.3% of KCl). A related species from warmer waters around New Zealand, Paranotothenia angustata, had similar vascular reactivity for NE (pEC(50) = 5.48 +/- 0.31 M), CBC (pEC(50) = 4.94 +/- 0.22 M), and methysergide-sensitive vasoconstriction with 5-HT (pEC(50) = 6.22 +/- 0.40 M). Agonist potencies were 9, 65, and 45% that of KCl, respectively. Bovichtus variegatus, a member of the phylogenetic sister group to the notothenioids, also gave broadly similar responses. In contrast, Dissostichus mawsoni, a pelagic Antarctic notothenioid, showed a dominance of vasodilatation over vasoconstriction, with sensitive isoprenaline (pEC(50) = 6.66 +/- 0.05 M) but weak serotonergic (5.2 +/- 1.5% KCl) responses. The unusual dominance of serotonergic control appears to be primarily a consequence of evolutionary lineage rather than low environmental temperature, but the pattern may be modified according to functional demand.


Original languageEnglish
Pages (from-to)R1197-R1205
JournalAJP Regulatory Integrative and Comparative Physiology
Issue number4
Publication statusPublished - 1 Apr 2001


  • serotonin, Antarctica, myography, catecholamines